Tamoxifen and the risk of ovarian cancer in BRCA1 mutation carriers.

BRCA1 mutation carriers have a high rate of both breast and ovarian cancer. Tamoxifen is a selective estrogen receptor modulator (SERM), which is used for the treatment of primary breast cancer and for the prevention of contralateral breast cancer. Our objective is to assess if tamoxifen treatment is associated with an increase in the subsequent risk of ovarian cancer among women with a BRCA1 mutation.A matched case-control study was performed. Cases were 154 women with ovarian cancer and a previous history of breast cancer. Controls were 560 women with no ovarian cancer and a history of breast cancer. All cases and controls carry a deleterious BRCA1 mutation. Cases and controls were matched for year of birth, age at diagnosis of breast cancer and country of residence. The effect of tamoxifen treatment on the risk of subsequent ovarian cancer was estimated using conditional logistic regression.The unadjusted odds ratio for ovarian cancer, given previous tamoxifen treatment was 0.89 (95% CI 0.54-1.49, p=0.66). After adjusting for other treatments, the odds ratio was 0.78 (95% CI 0.46-1.33, p=0.36).Tamoxifen treatment for breast cancer does not appear to increase the risk of ovarian cancer in BRCA1 mutation carriers.